On Fri 10-06-11 22:48:05, Wu Fengguang wrote:
> [It seems beneficial to queue this simple trace event for
> next/upstream after the review?]
>
> Add trace event balance_dirty_state for showing the global dirty page
> counts and thresholds at each global_dirty_limits() invocation. This
> will cover the callers throttle_vm_writeout(), over_bground_thresh()
> and each balance_dirty_pages() loop.
OK, this might be useful. But shouldn't we also add similar trace point
for bdi limits? Otherwise the information is of limited use...
Honza
>
> Signed-off-by: Wu Fengguang <fengguang.wu@xxxxxxxxx>
> ---
> include/trace/events/writeback.h | 36 +++++++++++++++++++++++++++++
> mm/page-writeback.c | 1
> 2 files changed, 37 insertions(+)
>
> --- linux-next.orig/mm/page-writeback.c 2011-06-10 21:52:34.000000000 +0800
> +++ linux-next/mm/page-writeback.c 2011-06-10 22:08:26.000000000 +0800
> @@ -430,6 +430,7 @@ void global_dirty_limits(unsigned long *
> }
> *pbackground = background;
> *pdirty = dirty;
> + trace_global_dirty_state(background, dirty);
> }
>
> /**
> --- linux-next.orig/include/trace/events/writeback.h 2011-06-10 21:52:34.000000000 +0800
> +++ linux-next/include/trace/events/writeback.h 2011-06-10 22:25:33.000000000 +0800
> @@ -187,6 +187,42 @@ TRACE_EVENT(writeback_queue_io,
> __entry->moved)
> );
>
> +TRACE_EVENT(global_dirty_state,
> +
> + TP_PROTO(unsigned long background_thresh,
> + unsigned long dirty_thresh
> + ),
> +
> + TP_ARGS(background_thresh,
> + dirty_thresh
> + ),
> +
> + TP_STRUCT__entry(
> + __field(unsigned long, nr_dirty)
> + __field(unsigned long, nr_writeback)
> + __field(unsigned long, nr_unstable)
> + __field(unsigned long, background_thresh)
> + __field(unsigned long, dirty_thresh)
> + ),
> +
> + TP_fast_assign(
> + __entry->nr_dirty = global_page_state(NR_FILE_DIRTY);
> + __entry->nr_writeback = global_page_state(NR_WRITEBACK);
> + __entry->nr_unstable = global_page_state(NR_UNSTABLE_NFS);
> + __entry->background_thresh = background_thresh;
> + __entry->dirty_thresh = dirty_thresh;
> + ),
> +
> + TP_printk("dirty=%lu writeback=%lu unstable=%lu "
> + "bg_thresh=%lu thresh=%lu",
> + __entry->nr_dirty,
> + __entry->nr_writeback,
> + __entry->nr_unstable,
> + __entry->background_thresh,
> + __entry->dirty_thresh
> + )
> +);
> +
> DECLARE_EVENT_CLASS(writeback_congest_waited_template,
>
> TP_PROTO(unsigned int usec_timeout, unsigned int usec_delayed),
--
Jan Kara <jack@xxxxxxx>
SUSE Labs, CR
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